What’s Happening to my Corn Field? Top Leaf Death in Corn Back »

Figure 1. A corn field near Brookings, SD with Top Leaf Death. Note the necrotic tissue at the top and bottom of the corn plant with green tissue in the middle.

In the past couple of weeks, several South Dakota producers have noticed considerable top dieback in area corn fields (Figure 1). There are several things which could cause this phenomenon including environmental stress, corn borer damage, or anthracnose. Top dieback symptoms caused by pathogens are typically variable from plant to plant, not consistent across entire fields. Due to the growing conditions prevalent in 2018, most cases in SD are likely a natural part of the corn life cycle commonly referred to as Top Leaf Death (TLD).

As corn reaches physiological maturity, leaf senescence (death) begins. Typically, the prevalent school of thought has been that corn plant senescence begins at the bottom of the plant and progresses up the plant toward the ear and upper leaves. This is the result of the corn plant reallocating nutrients from vegetative tissue to the ear during the grain filling period. The same conventional wisdom has always taught that corn dying simultaneously from the top and bottom must have some type of problem due to late season stress. While that certainly may be the case in some situations, research since the 1970s has shown that the top-bottom pattern of senescence is not unusual and can be attributed to 1) warm, dry weather conditions during grain fill; and 2) excellent growing conditions. These types of growing conditions have been prevalent across many areas of SD in 2018.

Some of the reason that TLD is more noticeable this year is that we are way above normal on Growing Degree Days…corn is reaching black layer earlier than normal. In many years a frost occurs before TLD is observed. It’s important to note that Top Leaf Death can be very hybrid specific. In general, it seems that hybrids with a high rate of Top Leaf Death have more rapid grain drydown.

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